"We must all rectify mistakes, unite and rally around the revolution until we spread goodness and brotherly love throughout Egypt, in spite of the coup, the junta and their deluded troops and their provocateurs' murderous militias," a statement posted on the Muslim Brotherhood's official news website said Tuesday.
The Egyptian military removed Morsi from power in July amid growing frustration with his policies. A candidate from the Muslim Brotherhood, he was criticized for clinging too tightly to the movement's Islamic ideologies.
The Brotherhood said it was calling for a "million-man march" Wednesday, the day Morsi's trial for his alleged role in the death of protesters in December 2012 resumes. It was adjourned in November.
Egyptian leaders scheduled a referendum next week for a new constitution to replace the one adopted by Morsi's administration.
The British government issued a travel advisory Tuesday warning protests are likely on Jan. 14 and 15, the days for the referendum.
"You are advised to take particular care in the vicinity of polling stations and government buildings, and to avoid all demonstrations and large gatherings," the warning read. "If you become aware of any nearby protests, leave the area immediately."